For the past several decades, the scaling of features in integrated circuits has been a driving force behind an ever-growing semiconductor industry. Scaling to smaller and smaller features enables increased densities of functional units on the limited real estate of semiconductor chips. For example, shrinking transistor size allows for the incorporation of an increased number of memory devices on a chip, lending to the fabrication of products with increased capacity. The drive for ever-more capacity, however, is not without issue. The necessity to optimize the performance of each device becomes increasingly significant.
Semiconductor devices formed in epitaxially grown semiconductor hetero-structures, such as in group III-V material systems, offer exceptionally high carrier mobility in the transistor channels due to low effective mass along with reduced impurity scattering. Such devices provide high drive current performance and appear promising for future low power, high speed logic applications. However, significant improvements are still needed in the area of group III-V material-based devices.
Additionally, in the manufacture of integrated circuit devices, multi-gate transistors, such as tri-gate transistors, have become more prevalent as device dimensions continue to scale down. Many different techniques have been attempted to reduce junction leakage of such transistors. However, significant improvements are still needed in the area of junction leakage suppression.